Adding Artwork - Crashes and Make Video White - HELP

I've ripped an episode of Stargate Atlantis to see what it was like in iTunes. It added and went straight into the MOVIES tab, I clicked "Get Info" and changed the settings under the "Video" tab to TV Show.
Then when I go to "Artwork" and delete the screenshot given, and add the poster/cover it appears... But everytime I click OK the "pizza of death" appears and the iTunes freezes.

I Force Quite the application, restart, and nothing has happened with the file. When I try to play it, its only a white screen. The time begins ticking, but there's picutre or sound.

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